While neat technically speaking, I unfortunately can't say the result is acceptable for any kind of professional work, in my opinion.

For example, take a close look at the iPhone X in the "Device Library" list, the device and "notch" borders are butchered beyond recognition. A key component of the iPhone X's brand are the particular rounded corners used for the notch, and if the point of this project is to closely emulate particular devices instead of generic ones, it woefully missed the mark.

To be fair, I can't speak for the accuracy for the other devices included, but if their implementations are at all similar to the iPhone X's, I'd expect they are also poor representations.

I understand your point of view, but I feel you're missing the purpose of these devices. The aim is not to provide a photo-realistic depiction of each device, but a representation that could be used on a landing page or a demo page.

We've found them to be adequate in situations where we require a responsive device frame, and I'm hopeful others will too.

Having said that, we will take another crack at the iPhone X to improve the shaping further. I think we can certainly get the rounded corners more in line with the actual shape. The notch may still be tricky though!

A demo isn't the product. Sometimes little details matter. Sometimes they don't. It depends on who is selling what to who...when. The rounded corners all matter if the sales pitch hinges on design. Simulating an iPhone X matters less if the pitch is earlier and about basic function. What and how much to include in a demo varies. Most of it is between pitch perfect simulation and nothing.

Just a design note on your product landing page: the big gradient "responsivedevices.css" in your hero looks like a big CTA button, although not clickable. Might want to change that, or make it direct to something.

I don't think it's against the rules of HN or GitHub. To be fair, it is a small fee, and helps fund the adding of new devices. At the end of the day, dev time is not free, and this took many days of research and development to perfect :)

The borders are not really borders, but a slightly larger element (scaled by a relative percentage) layered under the element we want to add a border to. That way, as the device scales up or down, the "border" also appears to scale!